Tjokroaminoto was born the second of twelve children, in the
Ponorogo Regency as the son of RM. Tjokroaminoto (district chief of
Kleco), grandson of RMA. Tjokronegoro (regent of the Ponorogo Regency), and great-grandson of Kyai Bagus Kasan Besari of Tegalsari
pesantren. According to his genealogy, his education was directed towards civil service. After graduating in 1902 from OSVIA (), a school for indigenous civil servants, in
Magelang, the then-highest civil servant education institution, he worked as one in
Ngawi for three years from 1902 to 1905). He moved to
Surabaya, where he met
Samanhudi, founder and leader of the Islamic Trade Unions (SDI). At night, he attended
Burgerlijke Avond School (BAS) for some years. After graduating, he worked in a
sugar refinery (1907–1912). He wrote for the
Bintang Soerabaja (
Surabaya Star) daily and became a staff assistant. Known as the "Crownless King of Java" () by the Dutch, Tjokroaminoto was one of the pioneers of the trade union movement in Indonesia and was a teacher of some of the most well-known leaders of Indonesia. His political ideas also gave birth to various ideologies of Indonesia at that time, when he tutored students in his household, such as
Semaoen,
Alimin,
Musso,
Sukarno,
Kartosuwiryo, and even
Tan Malaka. He was the first to refuse to submit to the Netherlands. After he died, the colors of the Indonesian movement were developed by his students, the
socialists and
communists embraced by Semaoen, Musso, and Alimin. One of his most famous quotes was "Highest education, purest
tauhid, smartest of strategies" (), depicting the atmosphere of Indonesian struggle in its time which required the three aforementioned abilities of a freedom fighter. Of the various students he liked most was Sukarno until he married Sukarno with his daughter
Siti Oetari, Sukarno's first wife. His message to his disciples was "If you want to be a great Leader, write like a journalist and talk like an orator". These words influenced his disciples to make Sukarno shout every night to learn the speeches to make his friends, Musso, Alimin, SM Kartosuwiryo, Darsono, and others wake up and laugh to watch it. ==Formation of Islamic unions==